Injection molding machine



G. THlLENlUs )2,233,354

INJECTION MoLDING MACHINE Filed nec. 5, 193s 4 sheets-sheet 1 Feb. 25,19.41.

Nw, w www INVENToR Ger/ard 77zenw BY Hls ATroRNYs Feb. 25, 1941. G.THlLx-:Nlus 2,233,354

INJECTION MOLDING MACHINE Filed Dec. 5, 1936 4 Sheets-Sheet 2 INVENTORGerhard 77zenus www HIS ATTORN YS Feb. 25, 1941. l G. vTl-uLEmls'2,233,354l

INJECTION HOLDING MACHINE IS ATTORNEYS 4 Sheetsl-Sheet 4 INVENTORGerhard T/zziuus BLW His ATTORNEYS G. THILENIUS Filed Dec. 5, 1936INJECTION MOLDING MACHINE Feb. 2.5, 1941.

Patented Feb. 25, 1941 INJECTION Momma MACHINE Gerhard Thilenius,Cologne-Klettenberg, Ger-` many, assignor to Eckert & Ziegler G. m. b.H., A(lologne-Braunsfeld, Germany Application December 5, 1936, SerialNo. 114,302 I In Germany March 23, 1936 6 Claims.

This invention relates to an injection molding machine for themanufacture of molded articles from thermoplastic material. In armachineof this type, it is known to extrude thermoplastic material confined ina cylinder through a nozzle into a two-part injection mold by the highpressure action of a ram upon said material. Originally, all motions ofthe mold parts and of the ram were controlled manually, but automaticregulation was soon developed. For this latter purpose, hydraulic aswell as electric driving means have been suggested. Hydrauliccontrivances are` disadvantageous due to complicated structure anddependence upon the generation of operating means at high pressure, suchas compressed air. Also, known electric ttings are unsatisfactorybecause they require separate driving motors and gears of specialconstruction for opening and closing the mold and for activatlng theram.

It is therefore an object of my invention to provide improved automaticregulation of the machine. A further object is to coordinate the motionsof the mold press and ram in desired succession. Another object are themeans involving such coordination.' I also aim to provide one singleactuating means for said coordinating element. Moreover, it is my objectto provide means for automatically controlling the action of saidcoordinating means with respectv to the motions of the mold press andram. This and further objects will clearly appear from the detaileddescription following hereafter.

The accompanying drawings illustrate the details and characteristicfeatures of my new machine as one embodiment of the invention.

Fig. 1 shows a sectional view of the machine. Fig. 2 is a plan view.Fig. 3 is a sectional view along line A--B of Fig. 1. l

Fig. 4 is a sectional view along line C--D and Fig. 5 is a sectionalview along line E-F of Fig. 1.

Fig. 6 is a sectional view of the machine somewhat similar to that ofFig'. 1, but showing the machine in a different operating position.

Fig. 'I is similar to Fig. 3 and -is a. sectional v-iew along line A-B`of Fig. 6.

Fig. 8 is a diagrammatical view of the wiring system.

Referring to Fig. 1, the frame of the injection molding machinesubstantially consists of two side plates I and crossheads 2,3, 4, 5, 6and 1, which separate the plates as well as rigidly connect them.

Two longitudinal struts 8, 8a are firmly secured to upper cross-heads 3,5 and 6, upon which there are displaceably mounted the cross-head- II towhich is attached the other struts 8, 8a serve to normally holdcross-head II in abutment with adjustable stopsl I3. The springs I4 abutwith their other ends on the xed cross-head 5. This cross-head carriesthe cylinder I5 which in known manner is provided with a feed opening I6and a nozzle orifice I1. The nozzle orice is arranged on a line with theextrusion opening of the injection mold provided in the mold part I2.

The upper fixed cross-heads 5. and 6 are furthermore joined by twolongitudinal struts I 8, I8a, on which a cross-head I3 is displaceablymounted. This cross-head is joined with ram 20 in which the cylinder I5is mounted for displacement in longitudinal direction.

Two rods 2l, variable in length, link displaceable cross-head I6carrying the mold part 9 and arms 22 of the double levers 22, 23. Rods23, which with one endl are linked to lugs 25 of crosshead 26 are, withtheir other ends, linked to arm 23 of levers 22, 23, which in turn aremovabl mounted on xed cross-head 3. v

I3 which carries'the ram 20, and double levers 28, 29 movably mounted tothe iixed cross-.head 6. The lower arms 29 of the double levers 28, 29and lugs 3| of displaceable cross-head 32, are linked by means of rods30.

The lever Isystems 2 I-24 on the one hand, and 21-30 on the other hand,form two systems of knee-levers for moving the displaceable crossheadsIIl and I9.

The cross-heads 26 and 32 are slid'ably mounted on two longitudinalstruts 33 and 33a, which are carried by the lower fixed cross-heads 2and 'l (see Fig. 3). Moreover, a further cross-head 34 is displaceablymounted on these two struts between cross-heads 26 and 32. 'Ihe path ofcross-head 26 is dened by stop sleeves 35 on one side, and 36 on theother side, whichsleeves are arranged on the longitudinal struts 33 and33a.

Similarly, the path of cross-heads 32 and 34 is limited bythe stppsleeves 36 on the one side and bythe sleeves 3l on the other side whichare provided on the right-hand ends of struts 33, 33a.

A rotary spindle 38 is longitudinally and movably mounted in the lowerxed' cross-heads 2 and 4 and rests with its free right end in a bearing39 fastened to cross-head 34, which end has a stop 40 which fits intothe recess of bearing 33 so that cross-head 34 is forced to followlongitudinal displacements of the control spindle 38.

A threaded portion 4I is located between crossheads 4 and 34, and'extends through the bore of cross-head 26 which is threaded to receive.portion 4I.

A cogwheel 42 is fitted upon that part of the control spindle 38 whichis positioned betweenthe iixed cross-heads 2 and 4. This cogwheel isfastened to this spindle by means of a key 43 Rods 21 link the upperdisplaceable cross-head and of a longitudinal groove 44 provided in thespindle so 4that it transmits rotating movements to the spindle, butdoes not prevent the spindle from being longitudinally displaced withrespect to its own position. A gear 45 which is mounted upon a shaft 46meshes with the cogwheel 42. The shaft carries a pulley 41 which islinked by meansrof belts or the Vlike 48 with a pulley 50 provided onthe shaft of an electric motor 49.

Two bolts 5I are fastened to the cross-head 34 and extend throughcorresponding borings of cross-head 32 and are each provided with animpact cap 52 serving as a stop for cross-head 32. The bolts 5I carrysprings 53 arranged lbetween the cross-heads 32 and 34, which springsnormally separate the cross-heads by a distance, as illustrated in Fig.3, which is determined by the length of the bolts 5I.

The displaceable'cross-head 26 has ateach of its two ends a lug 54 whichextends through an opening in the side plate I of the machine and into aslit'55 of.a control rod 56 mounted on the machine frame forlongitudinal displacement. In the position of cross-head 26 illustratedin Fig. 3, the lug 54 abuts on the righthand limit of the slit 55, andhas therefore moved the control rod 56 into its right-hand terminalposition. In this terminal position, a

lug 51 provided on control rod 56 has released a lock bolt 59 which isunder the action of a. spring 58 and which with its front end hasentered recess 60 of cross-head 34. In this manner, the cross-head 34 isprevented from being displaced longitudinally on' struts 33 33a. Whencrosshead 26 has arrived in the left-hand terminal position asillustrated in Fig. 1, the lug 54 has been abutted on the left-handlimit of slit 55 and has moved the control rod 56 into the left-handterminal position (Fig. '7)- in which the lock bolt 19 is moved out ofits locking position by means ofthe lug 51 so that cross-head 34 isfreely movable on the struts 33, 33a.

On each side of cross-head 34 there is mounted in a cylindrical recess apiston assembly 6I 5 which normally is in its front terminal positionunder the action of a spring 62 provided in the cylindrical recess. Thepiston rods 6I each act upon one arm of a lever 63 movably mounted onthe sleeves 36, While the other end of the lever acts upon the controlrod 56. When cross-head 34 reaches the left terminal position asillustrated in Fig. 3, the piston rods 6I meet levers 63, which by theirrotary movement displace the control rods 56 so that the lock bolts 59under the action of springs 58 will lool; cossheai 34 by means of recess80.

'I'he mode of operation of follows:

Atv the -beginning of an injection operation,

the machine is as the parts of the. machine' have the positions ll-lspectively are moved towards the mold part I 2,.

by means of the knee-lever system 2I24. This movement will continueuntil mold part 8 abuts on mold part I2 and until the mold no w closedbolts 59 are moved outof recess 60 of cross-head has been moved togetherwith cross-head II so .far against fixed cylinder I5 thatthe injectionopening of the mold is rmly pressedagainst the nozzle opening I1 of thevxedcyllnder I5. A t

-this moment the parts have the terminal posi- 5 tions illustrated inFigs. 6 and 7. Shortlypefore this terminal -position is reached, thelugs 54 of cross-head 26 move the control rods 56 into the left-handterminal positions so that the lock 10 34 by means of lugs 51.

Thereupon, cross-head 26, whicncannot be moved further due to theabutment of the `closed mold 3, I2 on the nozzle end of the fixedcylinder I5, becomes a fixed support for the spindle 38, which uponfurther rotary movement threads its way through the threaded boring ofcross-head 26 and moves to the right in a longitudinal direction.Accordingly, cross-head 34 is now moved to the right on struts 33, 33a;thereby it pushes along cross-head 32 by means of strong 4springs 53which at this'time are not compressed. The movement of cross-headV 32is' transmitted to cross-head I9 and thus to ram 2|! by. means ofknee-lever system 21-30. The indectionoperation is now performedin'which the injection material confined in the. cylinder- I5 is'transferred under high pressure through nozzle I1 into the closedinjection mold 8, I2.

The knee-lever system 2I-24, by adjusting the length of rods 2l, issuitably regulated so that the knee-levers 2l and 22 do not reach theirextreme position when the mold is closed, and crosshead 26 has also notas yet been broughtinto abutting position against sleeves 35. In thiscase, the pressure for closing the mold is equalized bythe pressureexerted on ram 26; i. e. with inv creasing pressure in the cylinder I5,the parts of vthe mold will likewise be pressed together more mly. I

Y Until the driving motor 49 is switched oil', crosshead 34 will keep onmoving with simultaneous compression of springs 53. Thus, these springsact as buiers which, after termination of the injection proper, absorbthe power which continues |to be introduced into the driving means;damagefor excessive stress of the machine parts are thus avoided.

Upon compression of' springs 53, the bolts 5I move through the boringsof cross-head 32, as shown in Fig. '1; l

v.The return of the machine parts subsequent to the injection operationtakes place in reversed order. l The direction of rotation of thedriving motor 49 and thus-of the control spindle 38 is 55 reversed sothat the control spindle moves towards the left in the cross-head 26which acts as a'n abutment, and thereby moves the crosshead 34 by meansof stop 48. The springs 53 are released and bolts 5I pull cross-head 32along by means of their caps 52, in consequence whereof the knee-leversystem 21-38 and the ram 20 are returned into the initial positionsillustrated in Fig. l.

As soon as cross-head 34 abuts on sleeves 36, the longitudinaldisplacement of the control spindle 38 is discontinued and from thispoint on the spindle will 4execute only a rotary movement. 'Ihe controlrod 56 has been returned into its initial position as illustrated inFig.3- byV the action *of piston rod 6I and lever 63; in this position thelockbolts 59 enter recesses 60 of cross-head 34 and lock the latter inplace. v

Upon further movement of the control spindle, vv cross-head 28 likewisemoves towards the right I5 into its initial position, whereby thiscross-head moves cross-head I towards the left by means of theknee-leversystem 2'I--24, so that the mold 9, I2 is re-opened. Likewise cross-headIl which carries the mold part I2, under the action of springs I4,returns to its initial positionwhich is fixed by stops I3. In thisposition, the injection opening of mold part I2 is distanced from thenozzle orifice of the cylinder. As soon as cross-head 26 abuts onsleeves 35, the

cycle is finished and motor 49 is turned oif.l

The machine is then ready for new operation.

Fig. 8 schematically illustrates the necessary electric wiring systemfor the control of driving motor 49.

'I'he three phase electric motor 49 is fed from the line 12 by way of areversing switch 10 y and of a relay 1I of customary construction. The

main control contacts At and A2 are arranged in the phase circuit whichleads into the injection molding machine. 'Ihe contact AI is opened bymeans of a control attachment provided on cross-head 26, whereby thesupply of current for the motor 49 is shut off as soon as cross-head 26has reached its initial-position, which corresponds with the positionillustrated in Fig. 1.

Contact A2A is carried by cross-head 32 and opened by cross-head 34 assoon as the latter approaches cross-head 32 at the end of the injectionwith'compression of springs 53. Like` wise in this case, the motor isshut off upon opening of the contact.

. vA contact A3 provided on the stop sleeve 31 is located in the samecircuit as is contact A2 and its purpose is to shut of! the current formotor 49 in the event that cross-head 32 should reach its extreme rightterminal position, which is iixed by the stop sleeves 31, withoutallowing crosshead 34 to approach it with compression of springs 53.This will occur, for instance, when the cylinder I5 contains no or notsuiiicient quantity of injection material.

Two further contacts A4 and A5 are provided in the same circuit` as iscontact A2, of which contact A5 is normally open, but is closed'byimpact sleeve 35.. The contact A4'on the other hand is opened at eachworldng stroke of the machine by means of a control lug 14 provided oncrosshead 34.

In normal operation, contact A5 is first closed by cross-head 26. sothat after the subsequent opening of contact A4, the supply of currentfor the motor by way of the auxiliary circuit 15, which passes overcontact A4 is assured until contacts A2 or A3 which switch off themotor, are opened.

Contacts A4 and A5 are provided for reasons of safety. If cross-head 25does not completely move into its left-hand terminal position, but isstopped prematurely by any foreign substance located between mold parts9 and i2, further operation is discontinued by the opening of con- VtactA4.

relative to one another, a rigidly mounted injec. tion cylinder, one ofsaid mold members being mounted to engage the injection cylinder andhaving `a sprue opening, and with a nozzle on said cylinder seatable insaid sprue opening, the improvement of the mechanism to open and closethe molds and reciprocate the injection plunger in the cylinder whichcomprises a rotatable shaft having a driving gear adjacent one end,means for splining said gear to the shaft in such a way as to allow.axial movement of the shaft in the gear, a threaded portion onsaid shaftadjacent its other end, a threaded element slidably mounted onand'positioned near said other end when the mold is in open position, meansfor preventing rotation of saidelement on said shaft, locking meansprovided at said other end of the shaft to prevent axial movetudinaldisplacement of said shaft, and means connected to said other end ofsaid shaft and to said plunger operable through said longitudinaldisplacement to force the plunger into the injection cylinder andthereby eiect filling of the mold.

2. A device for injection molding in accordance with claim 1 wherein themeans for preventing rotation of the crosshead on the shaft is a pair ofstruts mounted parallel to the shaft. 3. A device for injection moldingin accordance with claim '1 wherein the locking means comprise arecessed crosshead in abutting relation with said other end of theshaft, arigidly mounted cylinder provided with a spring-actuatedlock-bolt adapted to engage said recessed crosshead, a cam adapted todisengage said lockbolt from the recessed crosshead against the actionof the spring, said cam being actuated by the threaded crosshead at theend of its movement toward said one end.

4. A device for injection molding in accordance with claim 1 wherein themeans attached to saidvother mold member and the threaded crossheadcomprises a knee-lever system, one member of which connected with saidother mold member is adjustable in length.

5. A device for injection molding in accordl ance with claim 1 whereinthe means connected to said other end of the shaft and the plungercomprises a knee-lever system and a slidably mounted crosshead inabutment with said other end of said shaft.

6. A device for injection molding in accordance with claim 1 wherein anelectric motor is provided to actuate the driving gear of the shaft,

a power circuit is provided to feed said motor,

and a plurality of contacts are arranged in said circuit operative to bebroken upon termination of the plunger stroke and upon return of themold parts and plunger into initial position.

GERHARD

